﻿using System.Linq.Expressions;

namespace Pfz.TypeBuilding.Blocks
{
	/// <summary>
	/// This class is returned when calling Using() on a FluentMethodBuilder.Body or
	/// on any of its sub-blocks. Instances of this class can be used to add the actions
	/// that you want to be executed inside the loop.
	/// </summary>
	public sealed class FluentLoopBuilder<TParentBuilder>:
		FluentBlockBuilder<TParentBuilder, FluentLoopBuilder<TParentBuilder>>,
		_ILoop
	{
		internal FluentLoopBuilder(TParentBuilder parent, FluentMethodBuilder method):
			base(parent, method)
		{
			ContinueTarget = Expression.Label();
			BreakTarget = Expression.Label();
		}

		/// <summary>
		/// Ends the actual loop and returns the containing block so you can add new
		/// actions to it.
		/// </summary>
        public TParentBuilder EndLoop()
        {
            return _EndBlock();
        }

		internal override Expression _CompileToExpression()
		{
			var innerBody = base._CompileToExpression();
			var result =
				Expression.Block
				(
					Expression.Label(ContinueTarget),
					innerBody,
					Expression.Goto(ContinueTarget),
					Expression.Label(BreakTarget)
				);

			return result;
		}

		internal LabelTarget ContinueTarget { get; private set; }
		internal LabelTarget BreakTarget { get; private set; }

		LabelTarget _ILoop.ContinueTarget
		{
			get
			{
				return ContinueTarget;
			}
		}

		LabelTarget _ILoop.BreakTarget
		{
			get
			{
				return BreakTarget;
			}
		}
	}
}
